Sam went back to Mirage city after he received the news and met with the emperor to confirm that the Palace of inheritance is indeed someplace that he wanted to enter and even showed him the token to make him believe.
After that, he went on to develop the business of the shipbuilding. The two factories are going to be working together and one of them is responsible for the engine and the second one would make the transmission systems that could help vary the speed of the boat or ship and the steering system that helps in navigating the ship along with the whole structure of the ship.
Why leave one whole factory to manufacture engines? That is because engines are going to be a separate business. After his ships are released into the market, many people will get some ideas with the engine and he doesn't want to monopolize every single idea that comes with the engine usage.
All he has to do is sell the engine and demand a price.
